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Prof. A. Klein: A look at his life and achievements, and into future of imaging in atrial fibrillation

Prof. A. Klein at the Cleveland Clinic in Cleveland, Ohio, the USA, for the past 27 years and is the Director of the Center of the Diagnosis and Treatment of Pericardial Diseases and a staff cardiologist in the Section of Cardiovascular Imaging. In addition, he is Prof. of Medicine at the Lerner College of Medicine of Case Western University and was the Director of Cardiovascular Research for over 20 years. He is also the president of the American Society of Echocardiography.

Prof. Klein is an echocardiographer with an interest in atrial fibrillation (AF). In the early 1990s, he worked on the role of transesophageal echocardiography (TEE) guided cardioversion in AF. He and his colleagues conducted the first randomized clinical trial to be published on the role of TEE-guided therapy in AF,1 which has significantly changed the practice of cardioversion in AF patients.

Spotting the potential of TE

Prof. Klein’s journey began with a conference held by the American Society of Echocardiography, where he noticed that TEE is a powerful instrument in visualising left atrial appendage (LAA) clots in AF. After he returned, he and Dr. Richard Grimm, a fellow at the time at the Cleveland Clinic, had a patient that needed cardioversion. They debated the proper approach to cardioverting the patient from AF to sinus rhythm. The traditional thinking was that these patients would need a blood thinner such as warfarin for at least 3 weeks prior to any cardioversion, and then for 4 weeks afterwards. Prof. Klein asked why they could not expedite the cardioversion by visualizing the LAA, where the clots form, and, if there was no clot, they could cardiovert successfully while on anticoagulation. They started a small pilot project at the Cleveland Clinic, which was very successful.

A bigger randomized clinical trial of 1,222 patients worldwide compared TEE-guided cardioversion or conventionally guided treatment, finding that the TEE-guided approach was a clinically alternative strategy to conventional therapy for cardioversion of AF.

Following that, Prof. Klein and his colleagues asked whether anticoagulation could be achieved faster with enoxaparin, which became the ACUTE II study. Most recently, Prof. Klein was involved in the multicentre X-VERT study, which found that oral rivaroxaban is an effective and safe alternative to vitamin K antagonists in the cardioversion of AF.

Prof. Klein considers himself very fortunate to have started his training in Canada, initially at McGill University in Montreal, and then the University of Toronto and the University of Ottawa. From there, he went to the Mayo Clinic and then to Cleveland. During this journey, Prof. Klein profited from having a series of mentors, most recently Drs Liv Hatle, Jamil Tajik and Jim Seward at the Mayo Clinic and Drs Bill Stewart and Jim Thomas at the Cleveland Clinic.

Prof. Klein also believes that a certain degree of drive and persistence is required to succeed, even if things do not always work out. Above all, he says that you need to have life and have fun, and enjoy your sports and family outside of work.

The future of imaging in AF

Prof. Klein believes that imaging will be increasingly important in AF, whether echocardiography, cardiac CT scans, intracardiac echo or fusion imaging combining CT and fluoroscopy.

For Prof. Klein, one of the big recent developments in recent years has been devices that exclude the LAA, with the Watchman Left Atrial Appendage Closure Device (Boston Scientific, Marlborough, MA, USA) already approved in the USA.

Prof. Klein also expects that the new oral anticoagulants (NOACs) will be refined further to help patients in AF. In addition, the population of patients who receives LAA excluders and NOACs will be clarified further and contrasted with those who receive warfarin. With clinicians exploring novel indications for the drugs and potential price falls, there may come a time when warfarin could disappear altogether.

These changes will be accompanied by refinements to surgical techniques, and an explosion of percutaneous transcatheter aortic valve replacement, as well as mitral and tricuspid valve procedures. Prof. Klein envisions that an older person who takes blood thinners and has AF, and needs a new valve, will eventually undergo concomitant valve percutaneous surgeries and LAA percutaneous procedures, which he describes as “one-stop shopping”.

The future will also see assessment of left atrial function. When electrophysiologists perform an ablation they do not have a good sense of the return of atrial function. Novel strain techniques measure the mechanics of the left atrium and determine whether the patient needs to be on blood thinners or not, which offers an avenue for research.

Together, these changes are leading to a convergence of the percutaneous fields, with cross-talk between structural heart interventional cardiologists and electrophysiologists and imagers, who are also competing for the LAA space. In the words of Prof. Klein: “It’s exciting to see where the field is going in curing AF.”


Klein AL, Grimm RA, Murray RD et al. Use of transesophageal echocardiography to guide cardioversion in patients with atrial fibrillation. N Engl J Med 2001; 344: 1411–1420.